1. Field of the Invention
The present invention relates to framing systems and, in particular, a structural roof framing system comprised of metal members which are preformed and interlocked to form a roof frame of improved structural integrity and of desired length and pitch.
2. Description of the Prior Art
The majority of residential house framing is accomplished with wood. Most roofing systems with respect to residential housing have in the past been fabricated and constructed of wooden rafters, wooden ceiling beams and, when required, wooden strut members to form the roof frame. Wood was the material of choice because of cost considerations. Attention had been given to fabricating roof systems out of metal, but they normally could not compete with the cost of conventional wooden trusses.
In the past, Murphy in U.S. Pat. No. 4,389,829 and 4,201,026 and U.S. Pat. No. 4,192,119 and U.S. Pat. No. 4,188,147 directed his attention to metal structural members which could be utilized in the construction industry and, in particular, for conventional housing.
Similarly, Madray in U.S. Pat. No. 4,551,957 has directed his attention to the construction of a structure utilizing metal structural members.
Murphy, in his U.S. Pat. No. 4,389,829, discloses a metal roofing system in which the rafter and the purlin or ceiling beam are secured together by a plurality of truss or web members. Similarly, Madray in U.S. Pat. No. 4,551,957 discloses a roof structure comprised of metal members in conjunction with his overall metal frame for a building.
A major shortcoming with respect to structural framing with respect to metal prefabricated members is the fact that the alignment and joining of the members could not always be accomplished in a manner to ensure structural integrity. Madray requires a plurality of specialized angle pieces as disclosed in FIGS. 10 through 21 to connect the various metal structural elements of his frame. These angle pieces contain a plurality of apertures for the receipt of fasteners. The plurality of fasteners used at each joint is required to ensure that the structural integrity can hopefully be achieved. However, there is no guarantee that either a majority or perhaps a minority of the fasteners are in effect in proper position with respect to the intersecting structural metal elements of the frame. These shortcomings also relate to the teachings of Murphy who discloses certain specialized pin arrangements to secure various structural members.
Interest in structural metal elements for framing is gaining new interest in light of environmental laws, increased demand and decreased supply which have greatly escalated the cost and reduced the quality of lumber used in house framing. Additionally, certain building codes, particularly in the south, have increased the cost of constructing or framing with lumber due to certain weather phenomena particular to the southern United States. As such, framing with metal structural elements can now compete with traditional wood and lumber framing from a cost effective standpoint.
Applicant has improved upon the teachings of Murphy to provide for a more secure metal roof structure in which the members interlock and are positively secured at each interlocking point by a single fastener. Applicant's design provides for a lightweight, yet sturdy roof frame, the elements of which can be preformed and packaged as in a kit, so that a contractor need only specify the length and pitch of the roof required and a kit containing all of the elements for such a truss or standard ceiling beam and rafter can be provided.